INTRODUCTION
Over the last several decades, dioxins have become the subject of intense public and scientific scrutiny. This is the result of not only their great toxicity but also their assumed widespread presence in the environment. The toxicology of dioxins has been addressed principally through studies of their mechanism of biological action using animal models and cell cultures systems. In addition the potential threat that dioxins present to human health has been addressed in only a limited manner through epidemiologic studies of populations known to have been exposed to dioxins. The environmental issues have been addressed through the study of the production, release and fate of dioxins and related substances. Although dioxins have been extensively studied during the last twenty years, the exact mechanism of toxicity of dioxins in biological systems and the extent of environmental distribution are unknown. This is due in part to a lack of a simplified method of assessing the exposure of biological systems to dioxin and related compounds.